To steal the omnipresent Nike slogan: Just do it. There is no "right" answer to the great conundrum of where to build more airport capacity for southern England. When every option causes major protests in marginal constituencies, the easiest course is to do nothing. So far, this has been the coalition's response. But it's dishonest politics and increasingly contemptible.

Why? Because all the major business voices the government says it listens to agree that Britain needs more capacity. And at a time when the economy is flat on its back, with no help coming from growth anywhere nearby, one of the few things even a Tory-led government can do is to create capacity for growth. Yes, there are good green arguments against any increase in growth, particularly in transport, but they are a million miles away from the stated beliefs of the people who are actually in charge.

There is nothing new about controversial and politically dangerous infrastructure projects, from the first railways to the Channel tunnel, from the original creation of London's Heathrow and Gatwick airports, to the first motorways and nuclear power plants. Victorian politicians just did it. The Macmillans, Wilsons, Heaths, Thatchers sucked their teeth – but in the end, they just did it. This lot, however, apparently won't.

For several months there have been mutterings and murmurings in Tory circles about a likely U-turn and a third Heathrow runway. Now, seemingly, we have to read the runes of the forthcoming reshuffle to assess what the government is thinking on the issue.

Will Justine Greening, the transport secretary, be moved out? She represents Putney, a constituency deeply affected by any Heathrow decision, and has repeatedly emphasised her opposition to a third runway. Will Grant Shapps be moved in? He has certainly been pressing his case, saying that we need to reconsider a third runway if we are to remain "a great trading nation".

Shapps is far from a lone voice. Owen Paterson, the Northern Ireland secretary, has also joined the campaign, saying growth in Northern Ireland will be hit without expansion at Heathrow. Add to that the Free Enterprise group of Conservative MPs, who back the idea and suggest up to £40,000 in compensation to householders, and you have a considerable turning of the tide.

The chancellor, George Osborne, said back in March that we had to confront the lack of runways in London. He's been listening to businesses, here and overseas, who complain that unless Britain runs more direct flights to developing economies like China, Chile, Venezuela and Indonesia, it will lose its valuable international connectivity and hub status. Heathrow will lose its position as Europe's busiest airport, and businesses will stop wanting to locate here. It's an obvious straw for an embattled chancellor to clutch at.

Meanwhile, London's irrepressible mayor, Boris Johnson, opposes any expansion at Heathrow but wants a Thames estuary airport – already nicknamed "Boris Island". Never slow to make political capital from government delay, Johnson accuses the government of "pussy footing" around, and says that attempts to kick the controversial decision into the long grass are "totally mad". But Zac Goldsmith, the independent-minded and environmentalist Tory MP for Richmond Park, promises to resign if a U-turn is announced.

The Lib Dems, in line with their green agenda, remain strongly opposed to any U-turn – but we have seen them overruled before. Think tuition fees. So, for now, we have another impasse, with last month's draft aviation policy framework announcement skipping over the question of whether or not the third Heathrow runway will be revived.

Labour doesn't find this issue easy, either. Remember it was Geoff Hoon, a transport secretary in the last Labour government, who approved the controversial plan for expansion back in 2009. That decision was reversed in the coalition agreement, and Ed Miliband says he opposes it too. But there are still respected Labour voices, including former chancellor Alistair Darling, who support the plan.

Just as with a long-term strategy for social care, the future of Britain's aviation policy is fatally flawed by a lack of guts, a lack of vision, and a craving for short-term popularity. Several Conservative MPs now admit the decision to cancel a third runway was a mistake, but it's perfectly clear why it was taken. David Cameron needed to win those seats in south-east London where homes are already blighted by noise from Heathrow. (I know, I live there.)

Yet with the coalition agreement stating categorically that there would be no third runway at Heathrow, how is trust in politics going to be revived if yet another promise is broken?

Let's hear the facts: a report commissioned by airport owner BAA says the UK risks missing out on trade with developing countries worth £14bn during the next decade if Heathrow is not expanded. China is planning 15 new airports by 2015. So yes, the UK could lose out. But then there are the environmental effects: Heathrow generates 50% of the UK's aircraft emissions already, and now is surely a time to be reducing, not increasing, emissions. The village of Sipson, comprising 700 households, would have to disappear – and thousands of other Londoners would suffer a big increase in noise pollution.

As with all major decisions, there are pros and cons, swings and roundabouts. But some kind of decision has to be made. Is "Boris Island" really a non-starter? How feasible is expansion at Gatwick, Stansted or RAF Northolt? What about much greater investment in the railways to curb domestic flights? Or are the economic arguments so great that runway three must go ahead?

I go back to where I started. There is no "right", self-evident, politically safe answer – Boris Island is vastly expensive and would take for ever; neither Gatwick nor Stansted are easy to expand; and Heathrow would be a big political U-turn, probably causing resignations. Yet something needs to be done. And we are now at the point when it's more important to take a decision – any decision – than to carry on mumbling. So, ministers, be open with us. Spell out the problems with all the options. Then, for God's sake, choose one. That's what the cabinet is there for – and if it can't take big, strategic decisions, it's barely a government.

• This article was amended on 28 August 2012. The original subheading used the word prevarication where indecisiveness was meant. Prevarication means "to speak or act falsely or evasively with intent to deceive" (Collins)